(a) Why does endosperm development precede embryo development in angiosperm seeds? State the role of endosperm in mature albuminous seeds

(a) Why does endosperm development precede embryo development in angiosperm seeds? State the role of endosperm in mature albuminous seeds.
(b)Describe with the help of three labelled diagrams the different embryonic stages that include mature embryo of dicot plants.

(a) As it provides nutrition for the developing embryo. It is an adaptation to provide assured nutrition to the developing embryo.Provides nutrition during and germination.
(b) The zygote(in the embryo sac) divides to pro embryo and subsequently to the globular, heart shaped and mature embryo as shown in the diagram.